Magnetoresistance of a quantum dot with spin-active interfaces

Abstract

We study the zero-bias magnetoresistance MR of an interacting quantum dot connected to two ferromagnetic leads and capacitively coupled to a gate voltage source Vg. We investigate the effects of the spin-activity of the contacts between the dot and the leads by introducing an effective exchange field in an Anderson model. This spin-activity makes easier negative MR effects, and can even lead to a giant MR effect with a sign tunable with Vg. Assuming a twofold orbital degeneracy, our approach allows to interpret in an interacting picture the MR(Vg) measured by S. Sahoo et al. [Nature Phys. 2, 99 (2005)] in single wall carbon nanotubes with ferromagnetic contacts. If this experiment is repeated on a larger Vg-range, we expect that the MR(Vg) oscillations are not regular like in the presently available data, due to Coulomb interactions.

9 pages, 6 figures, to appear in Phys. Rev. B

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Cited by in corpus (31)

• Spin effects in single electron tunneling
• Universality of the Kondo effect in quantum dots with ferromagnetic leads
• A spin quantum bit with ferromagnetic contacts for circuit QED
• Ferromagnetic proximity effect in F-QDot-S device
• Effects of different geometries on the conductance, shot noise and tunnel magnetoresistance of double quantum dots
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